Interesting discrepancy there, I wonder where Trevor came across the last bit, "the serial number, the last 4, 5 or 6 numbers were done after the bike was finished and in series as they came off the line"?

My thoughts are that the process for the unit twins would have been very similar to what Stuart has posted about the Triples.

Don't remember exactly where that came from but fairly sure it was from the VMCC.However it was in relation to pre-WW II bikes.Nothing to do with Y bikes, but seems to follow on logically.It was in relation to engine numbers that seemed to be wrong when compared to total production numbers.What I was told is that the last section was the "sequence" number and as such was the last thing done to the bikes.At that time motors were batched and not made against orders so the sequence numbers went on last so they could be dated to the actual model year as there was a year code on the engines, then there wasn't, then there was, then there wasn't, then there was. And as the range was large the volumes of some models were small so some motors could have been sitting in the fatory for two or more seasons. All that was needed was a type number so the engine got put in the right frame.This also explains things like the "HC" oft stamped with no relation to the engine number at all as it got put on before completion so as to ensure it got the required special parts and was put into the right frame then the sequence number was put in the space between. and the "Q" numbers for 1 season only on Empire Star 500'sLooking at pre matching numbers and the way they are stamped it looks like this practice was followed till the end or at least till matching numbers became a legal requirement in the USA.The only actual pages of despatch book I have seen ( photo of same ) showed three different models with the numbers being in sequence on a machine by machine basis not a model by model basis.It was used to measure final production and as proof to the Midlands Bank that the machines had been made for financial reasons and to the Minestry of Supply to obtain orders for more raw materials. I think there was some tax implicatons as well from what I have read the imput taxes on export bikes were less than the imput taxes on domestic bikes and it appears that this post war emergency measure did not end till around the Thatcher period .Now as far as I can make out by the late 50's BSA's tax avoidence scheme had become so massive that Midlands Bank could not cover it hence Barclays became involved. Midlands released finances according to stock values on the shop floor and this included all parts. Barclays on the other hand only released funds secured by completed ( thus saleable ) bikes.Barclays used the despatch records as proof that the machine had in fact been made where as Midlands used the order book to calculate how much money was needed to make the bikes that were guaranteed to be sold.

I have been following this thread for quite some time (although not in close detail ) and have oft thought that the actual reasons for the "Y's" was more financial & political than mechanical.BSA oft made changes to bikes mid season and generally they simply sent a dealers bulletin out with the "as of engine number xxxxxx" these changes have been made then list the parts & instructions needed if the dealer was to retro fit the modification and the credit to be given for doing so.Joe public did not need to know unless BSA was going to use the upgrade for PR or sales purposes so there was no reason to put any distinguishing numbers on the bikes . And if they did then we have the plain Y or a different prefix , ie C11G for oil feed to head.OTOH the banks & the ministry did need to know that a particular bike was returned & reissued, of failed to be despatched in the first place & was sent out against a different order than it was originally made to fill. Thus we get Y .Y or -Y

Shane & I oft mull over this when we wander about pretending to be a farmer ( him ) & a useless labourer ( me ) as we are both hopeless Beeserphiles and the farm has become the BSA orphanage for anything with the piled arms on it.

With respect to the entries that had obviously been added post production ( or season for that matter ) that appear on loose pages & inside the end covers he suspects that these were done to cover a shortfall in the projected previous seasons production which would have had implications for both tax & supply and this to a large extent explains numbers that appear two or three times. A little bit back room hocus pocus to make the actuality tally with the projections.

This is also supported by the fact that "Y" seem to be only found on USA exports and not on bikes originally sent domestically or to the Commonwealth and as we got our "allowance" after the USA contracts had been filled one would expect that our markets would have been chockers with " Ys " if they were a mid season mechanical modification but the only ones I have ever seen have been on USA imports.

It is easy to forget about the political & financial when out focus is wholly on the lumps of metal and to overlook the possibility that the funny numbers might have nothing whatsoever to do with the actual bikes but more to do with the company that made them

I have always believed this to be true, it made sence to me at the time but as one trained in the sciences I am always happy to be proven wrong.I have assumed also that this was the case till matching numbers came in and the frame number got moved from under the steering stem where it would be really hard to stamp after the bike was assembled. If others know better then let it be known.

Hi Guys--looking for some guidance here.Have looked in on this thread from time to time but not followed it closely.Followed up an opportunity quickly yesterday I bought (at a good price) a BSA Lightning.I am not saying what year it is in the hope that you can tell me.It is titled in NJ as a 1967.The frame # is A65LA15***The engine # is A65LA15***-Y (yes a dash Y)I bought it from a guy who bought it in 1969 from the first owner.It was originally supplied by a dealer in Lodi, NJ---only about 5 miles from the old BSA Eastern HQ in Nutley, NJ.Any thoughts/ideas about year and in particular which parts lists I should look at for parts would be very welcome.Thanks in advance for any info.

Most of us will recognize this as a 1967, despatched towards the end of October, 1966.Having said that, the seller's reasons for listing it as a 1968 are interesting.According to the seller, the original owner/purchaser of this bike is an old Triumph dealer who has apparently stated that he purchased this bike new in 1968, and that it was titled as a 1968. He also apparently stated that "here in the USA we would get left overs titled and sold for the next year as a new bike of that year". Easy to see how the later Y bikes would fit in here as well.

The serial number of this particular bike puts it just before the initial rash of numbers that were re-used in later years, although we do have one lower numbered example on the spreadsheet, A65TA 6031Y of 1969.You would expect that this bike should have been at whichever dealership it was destined for by mid November, 1966, in good time for the selling season of the 1967 models. From the information the seller has provided, it seems that it might not have finally got there until a year later. Wonder what the factory records say about this serial number?

Yes, in some U.S. states dealers were permitted to title unsold bikes as the next year's models. This practice was not permitted in later years, as there was too much confusion when the laterowners brought them in for service.

I once had this problem with a 1956 Triumph T110 whose owner INSISTED it was a '57, because the title said so.

This knucklehead wouldn't believe me, even when I showed him the Triumph parts books, which listed the beginnings of the serial number sequences for both years!

in some U.S. states dealers were permitted to title unsold bikes as the next year's models.This practice was not permitted in later years,

In a thread a while ago about 1970 triples, iirc John Healy related that Triumph actually instructed dealers to title unsold '69 T150's as '70, until it was pointed out that was illegal in certain states.

The March 1970 edition of one of the US motorcycle magazines has a picture of a T150 with a 'beauty kit', captioned "the new 1970 Triumph triple"; given that the first of the true '70 (VIN year letter 'D') triples weren't built 'til April, that has to be a '69 bike.

Just out of interest I bought a Trident a few weeks ago. It looked like a 71, was titled as a 70 and was in fact a 69.From my experience in US it was pretty common practice to title a bike with the year it was sold--not when it was built.HTH

Just out of interest I bought a Trident a few weeks ago. It looked like a 71, was titled as a 70 and was in fact a 69.From my experience in US it was pretty common practice to title a bike with the year it was sold--not when it was built.HTH

Yes-Two Alpha--I agree--when the Ogle designed Trident was introduced I thought it was awful.However--latterly I am beginning to think that maybe the design was before its time.So much so that I am going to reconfigure the 69 looks 71 back into a full blown Ogle 69.Tastes change through time I guess.

For 1969 the Italians got the Ogle design Trident with a red scalloped/black tank and chrome fenders. It was beautiful! We got the left over bile green from the bottom of the paint tank. Same tank and fenders - different as night and day!